Ball point writing instrument



March 11, 1952 P C, HULL BALL PYINT WRITING INSTRUMENT Filed Sept. 20, 1945 JNVENTOR.

Patented Mar. 11, 1952 BALL POINT WRITING IN SITRUlHENT Philip C. Hull, Janesville, Wis., assigner to The Parker Pen Company, Janesville, Wis., a corporation of Wisconsin Application September 20, 1945, Serial No. 617,518

1 Claim. l

This invention relates to ball-point writing instruments and has for its primary object to provide a simple, low-cost device of that character wherein the writing point is retractable into the holder and subsequently propellable therefrom into operating position by depressing a pushbutton at the back end of the holder.

Another object is to provide a writing instrument of the above-indicated character wherein the ball point and ink reservoir are incorporated in one self-contained unit which is easily removable for replacement or refilling when the ink supply needs replenishing.

The present invention is characterized by the provision of a two-position spring detent mechamsm which, on the one hand. holds the writing point in its projected position Securely enough to resist normal writing pressure but yieldable sufficiently to permit the writing point to be retracted in'to the holder by the application of pressure which is only slightly greater than the maximum writing pressure, and which, on the other hand, securely latches the writing point in its retracted position so that it cannot drop out of the retracted position except when propelled by actuation of the aforementioned pushbutton.

For purposes of illustration, a practical embodiment of the invention is shown in the drawings, wherein:

Fig. 1 is a longitudinal sectional view of a pushbutton operated ball-point writing instrument embodying this invention, the writing point being shown in retracted position;

Fig. 2 is identical with Fig. 1 except that the writing point,V together with the propelling and retracting mechanism, are shown in the projected or propelled position; and

Fig. 3 is a cross-sectional View taken along line 3-3 of Fig. 1.

The writing instrument illustrated comprises an elongate tubular holder I which includes a barrel 2 which may be of plastic material, and a tapered tip member 3 made, preferably, of metal and threaded into the forward end of the barrel.

Housed within the holder is a ball-and-cartridge unit 4 comprising an elongate cartridge 5 which serves as an ink reservoir and to which is attached a feed tube 6 in the front end of which is seated a ball point 1, which serves as the writing point of the instrument. The reservoir is filled with a viscous, paste-like ink which is conducted through the bore 6a of tube 6 to the back of ball 1. A coil spring 8 continuously urges the ball-and-cartridge unit toward its retracted position shown in Fig. 1.` v

(Cl. 1Z0-42.03)

2 Pressed hito the rear end of barrel 2 is a metal bushing 9 which serves as a bearing for the rear end of the ball-and-cartridge unit 4 while at the same time serving to hold in place a pocket clip I0 which is inserted through a slot II in the barrel wall. Clip I0 has a tail piece I0a which is clamped between the outside of bushing 9 and the inner wall of barrel 2. Threaded into the extreme back end of the barrel is a bushing I2 through which a plunger I3 extends. The forward end of plunger I3 has an integral flange I4 which bears against the back end of ball-andcartridge unit 4. This plunger also has a small head I5 at its back end on which is pressed a cup-like member I6, the rear end portion of which constitutes a push-button. The forward part of member I6 is slitted longitudinally to form a number of spring fingers I'I, each terminating in a bead or bulge I8.

The spring fingers I1 are of such length that when the pushbutton I6 is fully depressed and the ball-and-cartridge unit 4 is moved to its fully propelled position, the beads I8 extend beyond and snap behind the inner end 20 of bushing I2 normally holding the ball-and-cartridge unit in its forward or propelled position. The spring 8 is not of sufficient strength to overcome the holding effect of the spring flngers II and beads I8 but it is of sucient strength to hold the balland-cartridge unit 4 firmly against the plunger I3 and the beads I8 in rm engagement with the inner end 20 of the bushing I2 thereby positively positioning the writing point I for writing.

The rearward or retracted position of the balland-cartridge unit 4 is determined by an annular V-shaped groove I9 formed in the bore of the bushing I2. This groove is so located that when the beads I8 are fully seated -therein the writing point 'I is fully retracted into theV barrel as shown in Fig. 1. To retract the writing point to the position shownin Fig. 1, the user simply places the writing point against a suitable surface, as for example a desk blotter, and presses it back to a position flush with the outer end of the barrel tip 3. The V-shaped groove I9 is so located longitudinally that lwhen the writing point is moved as just described, the beads I8 engage the outer part of the lower tapered side wall of groove I9 which side wall, acting as a cam, causes the beads to snap or ride fully into the groove I9 under the influence of spring 8 which is then yieldably urging the ball-andcartridge unit 4, plunger I3 and pushbutton IB rearwardly. This results in the writing point being further and quickly retracted from the flush position above mentioned to the fully retracted position of Fig. 1. When the beads I8 are disengaged from the inner end of the bushing I2 by the aforementioned push action, the spring 8 is not depended upon to move the retractible structure to its fully retracted position because of the frictional engagement of the beads with the inner wall of the bushing, but the spring 8 does become effective as the friction is sufficiently reduced as the beads enter the groove I9. In the fully retracted position the spring 8 yieldably urges the ball-and-cartridge unit 4 against the plunger I3 but it is not of sufficient strength to disengage the beads I8 rearwardly from the groove I9.

It will be obvious from the foregoing that, with the ball-and-cartridge unit fully retracted as shown in Fig. 1, depression of the pushbutton I6 will result in the beads I8 being forced out of the groove I9 and the ball-and-cartridge unit being propelled forwardly against the action of spring 8 to its fully propelled position of Fig. 2. AS soon as the pushbutton It has been fully depressed, the beads I8 snap behind and into latching engagement with the inward end 20 of bushing I2 thus yieldably latching the ball-and-cartridge unit 4 in its propelled or projected position of Fig. 2. Retraction of the unit is accomplished as explained above. The ball-point is usually coated with ink which might soil the users clothing and this is avoided by fully retraeting the point into the holder.

The spaces between the spring fingers I'I provide vent passages leading from the interior of the barrel 2 except when the plunger I3 is substantially entirely depressed. Ball-and-cartridge unit 4, plunger I3 and pushbutton I5 are readily Withdrawable from the holder by unscrewing and removing bushing I2.

I claim:

In a writing instrument, a hollow elongate holder having a bore opening at its front end, a writing unit having a writing point at its front end, means slidably mounting said unit in said holder whereby it is capable of being propelled forwardly to project said writing point out of the front end of Said bore into writing position and of being retracted to move said writing point into said holder, said writing unit being of substantially the same diameter as said bore for the greater part of its length, a reduced diameter pushbutton engageable with said unit adapted to project out of the rear end of the holder, said pushbutton being operative, upon being depressed, to propel said writing unit forwardly, a plurality of circumferentially spaced, laterally movable, outwardly urged spring fingers secured to said pushbutton, said holder having longitudinally spaced circumferential formations for receiving said spring fingers, said circumferential formations and spring fingers having interengaging camming surfaces, said spring fingers when in one of said circumferential formations being operative to hold said writing unit in its projected position against ordinary writing pressure but yieldable to retractive pressure applied longitudinally to the writing point when said retractive pressure is substantially greater than ordinary writing pressure.

APHILIP C. HULL.

REFERENCES CITED The following references are of record in the iile of this patent: Y

UNITED STATES PATENTS Number Name Date 365,747 Hoffman June 28, 1887 370,881 Michael Oct. 4, 1887 1,173,865 Ries Feb. 29, 1916 1,701,263 Hentzel Feb. 5, 1929 1,775,068 Debenedetti Sept. 2, 1930 1,923,684 Markstein Aug. 22, 1933 2,258,841 Biro Oct. 14, 1941 2,264,962 Adams Dec. 2,` 1941 2,354,484 Simpson July 25, 1944 2,400,679 Biro May 21, 1946 FOREIGN VPATENTS Number Country Date 25,344 Germany 1883 52,732 Germany -1890 59,575 Germany -1891 202,325 Great Britain Nov. 6, 192,4 573,747 Great Britain Feb. 22, 1944 

